Fluid blow-off silencer

ABSTRACT

A generally-cylindrical blow-off silencer is disclosed to be used, for example, on a vent, as from a high-pressure fluid system. A diffuser unit receives fluid from the vent and divides it into a multiplicity of separate streams which are directed radially to impinge upon a housing that is lined with acoustic material, at least a portion of which material is provided to dampen the housing. Scoria (light-weight, permeable, porous mineral) is disclosed as a liner pack, to dampen, seal and absorb sound-energy, in combination with glass-fiber material, which also is employed in an acoustic-core structure.

United States Patent 119i Richards Dec. 4, 1973 [54] FLUID F SILENCERFOREIGN PATENTS OR APPLICATIONS [75] Inventor! Richards Santa Paula,22,089 1907 Great Britain .1 181/55 Callf- 1,292,669 4/1969- Germany181/47 B 10,047 189] Great Britain. 181/55 [73] Ass'gnee' f fg l 18,1551904 Great Britain 181/55 [22] Filed: Jan. 14, 1972 a PrimaryExaminerRichard B. Wilkinson Assistant ExaminerJohn F. Gonzales 21 A l.N 217 857 I pp 0 Att0rneyB. G. Nilsson et al.

[52] U.S. Cl. 181/50, 181/55 1 [51] Int. Cl. F0ln l/10 [57] ABSTRACT i[58] Field of Search 181/33 GA, 55, 71, A generally-cylindrical w-Silencer is disclosed to 131 47 B 3 C, 37 47 R, 57 42 50 be used, forexample, on a vent, as from a highpressure fluid system. A diffuser unitreceives fluid [56] R f s Ci from the vent and divides it into amultiplicity of sepa- UNITED STATES PATENTS rate streams which aredirected radially to impinge 2 392 559 1 94 v l8! 5 upon a housing thatis lined with acoustic material, at 471880 22? 2 least a portion ofwhich material is provided to 3 642,095 2/1972 Fujii ..--l-8l/47 Bdampen the housing. Scoria (light-weight, permeable, 1:612:212 12/1926 g81/33 G porous mineral) is disclosed as a liner pack, to 1,229,4346/1917 Flockham 81/47 3 dampen, seal and absorb sound-energy,'=incombina- 2,466,001 4/1949 Burwell..... 181/33 GA tion with glass-fibermaterial, which also is employed 3,073,684 1/1963 Williams 181/55 in anacoustic-core structure.

3,454,129 7/1969 Everett 181/47 B I 3,635,309 1 1972 Nemcansky et al.181 55 5 Chums, 2 Drawlng Figure? FLUID BLOW-OFF SILENCER BACKGROUND ANDSUMMARY OF THE INVENTION noise, dependingupon the pressure ratios thatare in,-

volved. Although individual characteristics and demands may vary', aconsiderable need exists for an improved acoustical system, that may beemployed to restructure during the release of a fluid stream;

In providing the blow-off silencer, several considerations arepertinent.For example, it isgenerally important that the silencer freely allowthepassage of fluid so as to avoid the development of significant internalpressures. It is also important that the silencer does not itself becomea source of noise. For example, in some applications, a sudden burst offluid, released from a high-pressure source may actuate a silencerhousing,

causing it to ring like a bell. In many applications,

the silencer also must withstand exposure to relatively high-temperaturefluids. Finally, perhaps more general considerations include: theeffectiveness. of the si-' lencer, itscost of production, thepracticality of its use, its ease of installation, .and its maintenancerequirements.

In general, the present invention is directed to an improved blow-offsilencer which offers little impedance to fluid flow, may be constructedto withstand elevated duce the noise attendant the operation of ablow-off temperatures and-is effective and economical. The silencerincorporates a. diffuser for dividing the blow-off stream of fluid intoa multiplicity of small radial streams which are directedin an expansionchamber to impinge upon an acoustic lining pack of energyabsorbingmaterial. The structure incorporates an external housing, whichislinedby the acousticenergyabsorbing material partv of which (scoria)serves both to absorbacoustic energy and to dampen the housing.Additionallining in a pack,.is separated by a housing sealand isprovided inthe form of. glass fiber material, which may also be employedin a core structure, concentrically mountedin the housingto permit therelativelyfree passage of released fluid.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE ILLUSTRATIVEEMBODIMENT As required, a detailed illustrative embodiment of theinvention is disclosed hereimThe embodiment merely exemplifies theinvention which may, of course, be constructed in various other forms,some of which may be somewhat different from the disclosedillustrativeembodiment. However, specific structural and functionaldetails disclosed herein are merely representative and in that regardprovide a basisfor the claims herein which define the scope of theinvention.

Referring initially to; FIG. 1, there is shown a tower structure 10 (ofa high-pressure fluid system) incorporating a blow-off stack l2containing arelief valve 14 (symbolically represented). At its upperend, the stack 12 is terminated by a blow-off silencer l6,'constructedin accordance herewith. Generally, as indicated, the. silencer 16 isaffixed coaxially to the stack 12 by a flange coupling 18. It is to benoted that the silencer 16 may be mounted horizontally, as well asvertically, and accordingly, angular offsets are not particularlycritical considerations.

In the operation of the structure, as indicated in FIG.

1, the tower 10 may contain fluid, e.g. steam, highpressure gas, or thelike, which under certain conditions is exhausted (for variousintervals) to the atmbsphere through the stack 12. The valve 14 may beopened under circumstances and by controls that are notparticularlypertinent to the structure hereof. when the valve 14 is opened, fluidisreleased from the structure 10, to be discharged to ambient pressure.

Generally, a stream of high-velocity fluid that is discharged into arelatively-stationary gas results in jet noise that may vary incharacteristics. The jet noise may be simply turbulence, or may furtherinclude shock noise, in the event that certain critical pressure ratiosexist. Such noise in the presence of people results in reduced workingefi'iciency for those in the proximity ofthe structure, as well ascontributing to general noise levels at remote locations, which disturband distract personnel and populace.

.In accordance herewith, the silencer 16 passes fluid from a stack 12with little obstruction, while attenuating the noise resulting from thefluid discharge. Specifically, as disclosed in detail below, the systemaccomplishes attenuationby: shifting the frequency of the noise (to amore efficient attenuation .level) and absorbing the acoustic energy atthe altered frequency while dampening the housing of the silencer.Consideringthe blow-off silencer 16 in greater detail, reference willnow'be made to FIG. 2in which the internal details of the silencer areillustrated.

The silencer 16 isprovided in a housing20 which is .substantially openat the top, and is closed at the bottom. Specifically, a cylinder 21 isclosed at thebottom (asshown) by a dashed end 22. The housing 20 maycomprise various materials, as steel and aluminum, to

provide arigid shellstructure. Generally, plate material of significantthickness has been found desirable in many applications. I

The bottom or lower end 22 of the housing 20 concentrically receives adiffuser 24 comprising a closed top dome 26 and a cylindricalsection-28. The lower 1 dially with regard to the cylindricalconfiguration of the silencer l6. I

Substantially the entire interior of the silencer .16 is lined withacoustic energy-absorbing material. Specifically, the lower portion ofthe silencer 16 (comprising the expansion chamber 32) is lined withsound energy absorbing, permeable, mineral particles, while the upperportion is lined with glass fibers. Concentrically within the expansionchamber 32, a perforated cylindrical metallic liner wall 36 defines anannular space that receives granular energy-absorbing particles 38. Asimilar layer of the particles 40 is provided between the end 22 and afacing perforated metallic circular liner wall 42. The liner walls 36and 42 may comprise heavygauge sheet metal, e.g. steel, perforated toeffectively hold the packs of particles 38 and 40, while providing thedesired acoustic performance.

The acoustic layer particles 38 and 40 may comprise any-of a variety oflight-weight porous acoustic energyabsorbing minerals, e.g. scoriaaslaglike pyroclastic ejecta markedly vesicular. The material inalternative. forms should be light-weight, permeable to fluid,noncompacting and able to withstand elevated temperatures. Generally, italso is important that the material in the layers of particles 38 and 40directly engage the interior of the housing in orderto provide dampeningagainst ringing.

Above the expansion chamber 32, a pair of acoustic sections 41 and 43are provided which contain cores 44, 46, 52 and 54. One or severalsections may be used in various embodiments. The acoustic section 41includes an upper pack 55 while the section 43 has a lower pack 56, bothof cylindrical configuration conformed to the walls of the cylinder 21.

The acoustic section 41 is separated from the expansion chamber 32 by: aspacer ring 34, extending about a spider of radial bars 62 and alabyrinth seal 63. The ring 34, and a similar ring 65 (immediatelyabove) are affixed (as by welding) to a cylindrical, perforated facing67 to define an annular space which contains scoria (in the illustrativeembodiment) to function as the labyrinth seal 63. Generally, the seal 63restricts the flow of high velocity air along the inside surface of thecylinder 21 which would otherwise blowthe glass fibers out of the pack56 through the perforated facing 67. It is.

to be noted, that the rings 34 and 65 have an outside diameter that issmaller than the inside diameter of the cylinder 21, to accommodatetemperature-size changes. Yet, the space is effectively closed by theparticles in the labyrinth seal 63.

The upper pack 55 is separated from the lower pack 56 byradially-extending bars 57 and 59, comprising a pair of spaced-apartspiders 57a and 59a. The lower spider 57a is welded to the housing 20and supports the elements therebelow. The gap or space between thespiders 57a and 59a accommodates temperature related dimensionalchanges. That is, the bars 57 are affixed to the cylinder 21 along withthe bars 81 which support the cores. 44, 46, 52 and 54 (along with thepacks 55 and 56). However, the bars 59 are not so fixed.

The cores 44, 46, 52 and 54 may be of a structure quite similar to thepacks 55 and 56, i.e. glass fiber layers closed by apertured facings.Specifically, as exemplified by the core 54 (upper external) eachincludes a glass fiber packing 71 held between a pair of concentriccylindrical facing walls 72 and 73 which are joined, topconcentric walls72 and 73 may be first separately and bottom by a pair of flat rings 74and 75.

In the manufacture of the silencer as disclosed herein, the housing 20.may comprise cylindrically-- drical liner wall 36 and the bottom linerwall 42 may be affixed together as a sub-assembly prio-r'to placementwithin the housing 20, with the material layers 38 and i 40therebetween.

Generally, the acoustic packs and 56, along with the cores 44, 46, 52and 54 may be formed as an integral sub-assembly forsubsequent insertionwithin the housing 20. Specifically, each of the cores, including theacoustic interior packing 71 contained between formed. The walls 72 and73 are perforated to hold the interior packing 71 while affording thedesired acoustical energy absorbing characteristics. Generally,'theinterior packing 71 may comprise fiber glass, light-weight minerals asscoria or vermiculite, stainless-steel spinnings, or other acousticenergy-absorbing materials.

In a sub-assembly operation, after forming the individual cores 44, 46,52 and -54 (as by metal shaping and welding techniques) the cores arefastened together between the sets of radial bars, e.g. bars 62, 57 and81 The division of the single stream into a multiplicity of separatestreams, shifts the frequency .to higher levels at which theacoustic-energy absorbing materials are more efficient. Additionally,the diffuser'24 decouples the' silencer 16 from the fluid system (stack12) to avoid resonance situations. Also, the diffuser 24 accomplishes atransition into the expansion chamber 32, thereby reducing the flowturbulence.

The fluid streams from the diffuser 24 are directed to' impinge upon thelined expansion chamber 32 which,

as indicated above, contain the layers of particles 38 and 40. Theselayers function not only to absorb acoustic energy but additionally todeaden or dampen the housing 20 against ringing. It is to benotedfthatthe labyrinth seal 63 (above the particles-38) prevents the fluidstreams from forcefully moving in, and behind the pack 56. Otherwise,forces would be created to displace the energy-absorbing material in thepacks.

Above the expansion chamber 32, the acoustic packs 55 and 56 function incombination with the acoustic cores 44, 46, 52, and 54 to attenuatesound by absorbing the acoustic energy. Specifically, the annularacoustic cores 44, 46 52 and 54 provide absorptive silencing to achieveeffective attenuation. The concentric annular core configuration enableseffective control over packing depth, while avoiding thick and thinspots which tend to decrease packing efficiency. The combinedcomponents, including the diffusenthe expansion chamber, the acousaticpack and the acoustic cores tends to afford a significantly improvedcombination for the effective reduction of undesired noise attendant afluid stream. The utilization of the particle material, and specificallyscoria as disclosed, has been determined to be very effective regardingthe durability of the silencer. Specifically, scoria has goodsoundattenuating characteristics, is relatively inexpensive, and tendsto resist settling or compressing, so as to 6 said housing to define anunobstructed open passage from said diffuser unit through said housingfor passing said separate streams to ambient.

2. A blow-off silencer according to claim 1 wherein one of saidenergy-absorbing structures conforms to an interior wall of said housingand further includes a terminal annulus of granular particles forclosingan end of said one structure. 7 Y

3. A blow-off silencer according to claim 1 including a plurality ofsubstantially cylindrical, energyabsorbing structures affixed inconcentric, spacedapart relationship within said housing.

maintain effective physical contact with the housing for dampeningpurposes. Of course, various other materi als and structures may beemployed herein in accordance with'the principles hereof, andaccordingly, the scope hereof is deemed to be as defined by the claimsas follow.

What is claimed is:

l. A blow-off silencer for use on a fluid-discharge passage, for passinga fluid stream to ambient, comprising: I g

a generally cylindrical housing-having a cross sec tional area greaterthan that of said passage and adapted to be connected to receive saidfluid stream;

i a diffuser unit affixed at one end of said housing for receiving saidfluid stream and for dividing said stream into a multiplicity ofseparate streams;

a perforated liner, spaced apart from a portion of said housing at saidone end, to define an annular space between said housing and said linerand also defin- 'ing an unobstructed open space extending from saiddiffuser unit through said housing;

a pack of granular energyabsorbing particles disposed in said annularspace to contact said housing; and

. at least one, substantially cylindrical energyabsorbing structurefixed in said open space of said housing and extending adjacent theopposed end of 4. A blowoff silencer according to claim 1 wherein saidgranular energy absorbing particles comprise permeable mineralparticles.

5. A blow-off silencer for use on a fluid-discharge passage, for passinga fluidstream' to ambient, comprising:

a generally cylindrical housing having a cross sectional area greaterthan that of said passage and adapted to be connected toreceive saidfluid.

stream; 1

a diffuser unit affixed at one end of said housing for receiving saidfluid stream and for dividing said stream into a multiplicity ofseparate fluid streams; a perforated liner, spaced apart from a-portionof said housing at said one end, to define an annular space between saidhousing and said liner;

a pack of granular energy-absorbing particles disposed in said annularspace to contact said housing;

cluding a terminal annulus of loose granular parti- 1 cles for closingan end of said structure against said fluid streams by contact with saidhousing.

1. A blow-off silencer for use on a fluid-discharge passage, for passinga fluid stream to ambient, comprising: a generally cylindrical housinghaving a cross sectional area greater than that of said passage andadapted to be connected to receive said fluid stream; a diffuser unitaffixed at one end of said housing for receiving said fluid stream andfor dividing said stream into a multiplicity of separate streams; aperforated liner, spaced apart from a portion of said housing at saidone end, to define an annular space between said housing and said linerand also defining an unobstructed open space extending from saiddiffuser unit through said housing; a pack of granular energy-absorbingparticles disposed in said annular space to contact said housing; and atleast one, substantially cylindrical energy-absorbing structure fixed insaid open space of said housing and extending adjacent the opposed endof said housing to define an unobstructed open passage from saiddiffuser unit through said housing for passing said separate streams toambient.
 2. A blow-off silencer according to claim 1 wherein one of saidenergy-absorbing structures conforms to an interior wall of said housingand further includes a terminal annulus of granular particles forclosing an end of said one structure.
 3. A blow-off silencer accordingto claim 1 including a plurality of substantially cylindrical,energy-absorbing structures affixed in concentric, spaced-apartrelationship within said housing.
 4. A blow-off silencer according toclaim 1 wherein said granular energy absorbing particles comprisepermeable mineral particles.
 5. A blow-off silencer for use on afluid-discharge passage, for passing a fluid stream to ambient,comprising: a generally cylindrical housing having a cross sectionalarea greater than that of said passage and adapted to be connected toreceive said fluid stream; a diffuser unit affixed at one end of saidhousing for receiving said fluid stream and for dividing said streaminto a multiplicity of separate fluid streams; a perforated liner,spaced apart from a portion of said housing at said one end, to definean annular space between said housing and said liner; a pack of granularenergy-absorbing particles disposed in said annular space to contactsaid housing; and a substantially cylindrical energy-absorbing structurefixed adjacent said housing and extending above said pack to a locationadjacent the opposed end of said housing to pass said separate streamsfrom said diffuser unit to ambient, said structure conforming to aninterior wall of said housing and further including a terminal annulusof loose granular particles for closing an end of said structure againstsaid fluid streams by contact with said housing.